Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $84.59   12.697%   $95.3304   $95.33   $95.35   $95.30  
  Purchase #2 $183.51   8.653%   $199.3891   $199.39   $199.40   $199.40  
  Purchase #3 $45.40   5.741%   $48.0064   $48.01   $48.00   $48.00  
  Purchase #4 $98.49   8.372%   $106.7356   $106.74   $106.75   $106.70  
  Purchase #5 $37.92   12.267%   $42.5716   $42.57   $42.55   $42.60  
  Purchase #6 $184.75   8.708%   $200.838   $200.84   $200.85   $200.80  
  Purchase #7 $21.76   6.762%   $23.2314   $23.23   $23.25   $23.20  
  7 purchase totals = $656.42       $716.1025   $716.11   $716.15   $716.00